In order to distinguish 45 nm target in the very large scale integrated circuit where the numerical aperture is 1.35 and its wavelength is 193 nm,it is necessary to analyze the error factors which affects lithography lighting uniformity,and eventually the tolerance range can be determined.Since the compound eye lens can make the light beam form rectangular uniform illumination area on the surface of mask,it is a key component in the lighting system.Through CODE V software,compound eye lens is designed,and the illumination non-uniformity is simulated and analyzed.Considering the compound eye lens design and actual processing,it is concluded that x-direct and y-direct compound eye curvature tolerance is ±10%,the back-group curvature tolerance is ±5%,the interval tolerance between front and back group is ±50 μm,the location accuracy of eccentric tolerance is ±1 μm,the assembly accuracy tolerance is ±3 μm.The results show that the tolerances are reasonable and feasible and can meet the requirements of high uniformity and high energy utilization of immersion lithography lighting system.